Certain physiological conditions which occur prior to more serious and permanent conditions or injuries are either not susceptible to detection or are detectable only on pathological specimens. Ischemia, for example, is a localized tissue anemia resulting from obstruction of the blood supply or from vasoconstriction. If sustained, ischemia can result in infarction which is detectable by various known scanning techniques. There is no known method of detecting ischemia short of infarction, however. Similarly, neuronal cell loss may be indicative of an underlying abnormality which can lead to infarction, but methods for detecting infarction may not show the extent of the areas of neuronal loss. The detection of both focal and global ischemia, neuronal loss and other pre-infarction conditions would serve to identify and localize the underlying abnormality and permit early treatment. Similar benefits would be achieved for such conditions as hypoglycemia, status epilepticus, and other types of stress or cell injury in brain and all other organs.